Genes play a significant role in persisting symptoms of ADHD

Children with higher genetic risk for Attention-Deficit/Hyperactivity Disorder (ADHD) are more likely to see their symptoms persist into their late teenage years, according to findings from the Avon Longitudinal Study of Parents and Children (ALSPAC).

For most children with ADHD, their hyperactivity and inattention fade as they get older. Children with other neurodevelopmental conditions, such as autism and communication or learning disorders, also see their symptoms lessen with time. However, a small number of children continue to display symptoms throughout adolescence and into adulthood.

Research led by the MRC Centre for Neuropsychiatric Genetics and Genomics analysed information on more than 9,700 young people born in the former county of Avon in 1991-92, who are being followed by ALSPAC. They looked at the children’s genetic risk for ADHD, and the likelihood that their symptoms lasted beyond childhood.

Only a small proportion – 4 per cent – were persistently hyperactive and inattentive from age 4 to 17. Just under 6 per cent exhibited these symptoms only in childhood, and the majority (over 90%) only ever displayed low or modest levels.

Children with the highest genetic risk for ADHD were the most likely to display symptoms through to late adolescence.

The most genetically predisposed to ADHD were also most likely to display other social and conduct problems in childhood, including low IQ, social communication problems, language difficulties and poor behaviour. For example, more than half of the children with persistent symptoms of ADHD had trouble with interpersonal communication, compared to just 3 per cent of those with low signs of the disorder. They were also significantly more likely to have multiple social and conduct problems.

The authors explained that the presence of other problems “may help to identify children with ADHD whose symptoms are most likely to continue into adolescence”.